Typically, two-shot injection molding assemblies are used in order to create a plastic part made of two different materials or two different colors of the same material or different material. A typical two-shot injection molding assembly will inject the first material into the mold while the area of the mold that is intended for the second material is blocked off. After that the mold is opened, the core plate is rotated, the mold is blocked off again, and the second material is injected into the mold. After the second material is injected, the material from the first and second injection touch and form a mechanical bond while cooling. However, an undesirable seam is created where the two different materials bond together, and cracking can occur if the first injected material solidifies before the second material is injected due to the differential shrinkage. Also, the time it takes to open and close the mold and rotate the core plate adds additional production time which raises the cost of production.
Accordingly, it is desirable to have an injection molding assembly with fewer limitations. It is also desirable to have an injection molding assembly that can finish the injection molding process by having only one injection molding cycle. In addition, it is desirable to have a dual material injection molding process that produces a seamless multi-material and/or multi-colored product.